The present invention relates to a flexible guide device, in particular for a welding wire, formed by a plurality of individual elements which are connected to each other in an articulated manner.
A guide device of this type may be used for guiding the welding wire used by a welding robot between a container for the welding wire and the welding head. The guide device must be flexible so as not to impede the movements of the welding head. Furthermore, the guide device needs to ensure that the welding wire can not kink because kinks in the welding wire would interrupt the automated welding process. Finally, the guide device is required to protect the welding wire from soiling and, in arc welding, from contact with other objects, if required, in order to prevent a short circuit.
A major part of the problems arising in automated welding is caused by the friction of the welding wire which occurs inside the guide devices in which the welding wire is guided from the welding wire container to the driving rollers of the wire feeding device and from there to the welding head. The friction leads to stress marks and deformations appearing on the surface of the welding wire. In arc welding, this results in a decrease in the conductivity, in problems with the electric arc, and in an impairment of the weld quality. If the chips produced by friction or the lubricant used to reduce the friction accumulate on the surface of the welding wire, this results in the welding wire being fed non-uniformly, in the guide devices being plugged up, and in problems with the arc at the welding head. If the welding wire is bent excessively on its path from the welding wire container to the welding head, the bent point which is then supplied to the welding head results in that the arc runs beside the place at which the welding seam should be actually located, which then requires expensive reworking steps.
In order to avoid stress marks on the surface of the welding wire, attempts have already been made to use welding wire guide devices made of plastic. However, the welding wire cuts through the plastic sheathing after a relatively short time so that considerable problems arise in the feeding. In the case of welding wire made of aluminum or an aluminum alloy or in the case of welding wire having a passivated surface, stress marks in the surface of the welding wire may cause considerable problems with the welding performance. All of these problems underline the significance of a low-friction feeding of the welding wire to the welding head.
An example of a flexible welding wire guide device is shown in WO 2007/010171 A2. This guide device consists of various individual elements, each individual element being connected to the neighboring individual element by a swivel bearing which allows a movement only about a particular axis. Bearing rollers or similar guiding formations for the welding wire are fitted inside the base bodies of the individual elements. All in all, this solution involves a very high structural expenditure and therefore very high costs.
The object of the present invention resides in providing a low-cost guiding device for a welding wire which allows the welding wire to be guided with low resistance and at low cost.